WO1985005728A1

WO1985005728A1 - COPOLYMERS AND MIXTURES OF POLYMERS WITH A CONJUGATED pi-SYSTEM

Info

Publication number: WO1985005728A1
Application number: PCT/EP1985/000189
Authority: WO
Inventors: Klaus Menke; Walter KLÖPFFER; Klaus Wollmann; Hermann Schomann; Peter Wiesert; Wolfram Krieger
Original assignee: Battelle-Institut E.V.
Priority date: 1984-05-26
Filing date: 1985-04-26
Publication date: 1985-12-19
Also published as: DE3419788C2; JPS61502261A; CA1269194A; DE3419788A1; EP0185063A1

Abstract

Electrically conducting copolymers and mixtures of polymers with a conjugated $g(p)-system with conventionally nonconducting polymers carrying isolated redox-active groups. These new substances have particular electric, electrochemical and chemical properties, together with the possibility of thermoplastic transformation and a typical behaviour of synthetic material.

Description

description

Copolymers and blends of polymers with conjugated ∏ system

Polymers with conjugated ∏ system, which after doping, d. H . Oxidation or reduction, becoming electrically conductive, can also be considered as redox-active polymers. Oxidation or reduction means electron withdrawal or input into the ∏-electron system of the

Main chain. The resulting charges are localized over large areas of the ∏ conjugation. You can also walk or hop along the chains between them, thus effecting charge transport when applying an electrical field and conductivity. Electronically, they change the band structure from the semiconducting or insulating state of the undoped polymer to that of a metal with an extended, partially filled band at the Fermi boundary. Structurally, they are organized into rigid microcrystalline areas that are detrimental to all plastic, mechanical and processing properties. An intrinsically conductive polymer of this type can neither be dissolved nor melted and can only be used in the form it takes after doping. In order to achieve mechanically usable and processable electrically conductive polymers, polymers with a conjugated ∏-system have to be blended as block or graft copolymers or blends with conventional macromolecules that form flexible soft segments. Guce conductivities connected Those with good mechanical properties and processability are always obtained when the most homogeneous distribution of the conductive component in the matrix of the conventional polymer is achieved. Copolymers and blends of polyacetylene of this type are already known (Galvin and Wnek, J. of Pσlym. Sei., Poiym. Chem. Ec. 21, 2727 (1983); Lee and Jopson, Makrom. Chem. Rapid Commun. 4, 375 (1933)). With a share of only 5%, conductivities are achieved that are at most one to two orders of magnitude lower than the conductivity of pure polyacetylene. However, the oxidatively doped conductive polyacetylene has the disadvantage that it decomposes again when stored and in the air and therefore loses its conductivity.

The present invention has for its object to produce stable and as easy to process intrinsically conductive polymers.

This object is achieved according to the invention in that the copolymers and blends are composed essentially of polymeric components (A) without a conjugated ystem system and polymeric components (3) with a conjugated ∏ system, component A having redox-active groups which are oxidized in or reduced state have an active potential which is sufficient for the oxidation or reduction of component B. Preferred embodiments are described in subclaims 2 to 12.

In the process according to the invention for the production of such copolymers and blends, redox-active compounds with polymerizable substituent are hemopolymerized or copolymerized in a manner known per se or are linked to polymers without a conjugated ∏ system by chemical reaction and the polymer component A thus obtained is obtained is mixed in a known manner with the polymeric component B or with the monomer forming the component B and is oxidized or reduced chemically or electrochemically. Subclaims 14 to 24 relate to advantageous variations of this method.

The copolymers and blends according to the invention are particularly suitable as electrical conductors or semiconductors, in solar cells, for antistatic finishing of plastics, as materials with low surface resistance, suitable for capacitive sensing, as materials for electromagnetic shielding, as battery electrodes, as electrode materials and as membranes for the Electrochemistry and fuel cells can be used.

The invention enables, in particular, polypyrrole, polythiophene and derivatives, such as substituted polypyrroles or polythiophenes, polymers from aromatic rings, pyrrole and / or thiophene units, and also polyanilines, which are obtained by oxidative polymerization of anillin, with non-conductive polymers (б ≤ 10 ^-8 s / cm) can be processed in a wide variety to copolymers or blends. Almost all conventional polymers, especially those with flexible and highly flexible chain forms, can be used as copolymers

Polypyrrole can be processed into electrically conductive plastics. A prerequisite for this is the presence of redox-active groups, which can either be bound as a side chain substituent or themselves can be polymerized into the main chain as a functional monomer. Particularly suitable redox-active groups are those which can be oxidized with high reversibility and reduced again and whose oxidation potentials are slightly above that of the polymer with conjugated "∏ system. For polypyrrole, polyaniline and alternating ones composed of aromatic and pyrrole rings For polymers, this is ideally fulfilled by the dicyclopentadienyl iron or ferrocene complex. The ferrocene complex can be reversibly oxidized at about +0, 4-0, 5 V compared to SCE and in this form, as ferricenium salt, can oxidize the aforementioned polymers with a conjugated ug system and make them conductive.

Polypyrrole e.g. B. has an oxidation potential of -0.2 V and polyaniline of +0.1 V compared to SCE. In the reaction with polymer-bound ferricenium salt, electrons are transferred to the ferrocene and anions to the polymer with conjugated ∏ system:

Nonetheless, ferrocene as a redox-active group in a blend consisting of polyphenylene or polynaphthalene pyrrole also enables electron and ion migration in the non-conductive part and thus brings about a quick and uniform doping of the conjugated polymer, which is not bound to freely accessible parts of the conductive component.

The binding of the ferrocane via substituents or directly to the cyclopentadienyl ring as a substituent on the side chain of a conventional is essential for the invention. Polymers, or a polymer in which a disubstituted ferrocene monomer is incorporated into the main chain by polycondensation, polyaddition or aromatic substitution on the cyclopentadienyl rings. Binding as a side chain substituent is e.g. B. possible by using polyvinyl chloride, polybutadiene, polyacrylate, polymethacrylate, copolymers of maleic anhydride and styrene, copolymers of butadiene and styrene, chloromethylated polystyrene or the like. a. with AICI ₃ and unsubstituted ferrocene. Depending on the Frozrocenantail, AICI _{3 use} , temperature and reaction procedure, weakly substituted uncrosslinked or highly substituted crosslinked polymers are obtained. Binding of the ferrocene is also possible by diazotization of the poly-p-aminostyrene and subsequent reaction with ferrocene or ferricenium salts, by reaction of the ferrocenecarboxylic acid chloride with -NH ₂ or -OH functionalized polymers, such as, for. B. polyvinyl alcohol and copolymers such as partially saponified polyvinyl acetate or polyvinyl butyral, further poly (1-hydroxypropen (2)) polyhydroxyethyl or hydroxypropyl acrylate or methacrylate and copolymers thereof, poly (1-aminopropen (2)), poly (p -aminostyrene), poly (p-amino-styrene), poly (p-amino-α-methystyrene), polyvinylamine and copolymers thereof, and copolymers of aminopropyl-triethoxysilane and siloxane oligomers.

It is also possible to bind hydroxyalkyl ferrocene to copolymers containing carboxylic acid chloride, sulfonic acid chloride or anhydride substituents or by esterifying copolymers of acrylic acid.

The introduction of the ferrocene chain into the side chain of polymers also succeeds by mono- or copolymerization of monomers which contain the ferrocene ring bound to a substituted polymerizable group. For this z. B. vinyl and divinyiferrocene, ferro cenylmethyl methacrylate or acrylate, ferrocenylmethyl acrylamide, ethynyl ferrocene, p-ferrocenylstyrene, p-ferrocenylphenylacetylene and the like. a.

Integration of the ferrocene in the main chain can e.g. B. by polycondensation or polyaddition with suitable substituents. For example, B. Reactions of terminally diamino or dihydroxy-substituted monomers or prepolymers with ferrocendicarboxylic acid, dicarboxylic acid ester or dicarboxylic acid chloride,

Ferrocene diisocyanate or ferrocene dialkyloxirane.

Conversely, dihydroxylalkylferrocenes with monomeric dicarboxylic acids or carboxyl-terminated polyesters, with monomeric or oligomeric diisocyanates or prepolymeric epoxy resins can be converted into polymers with a ferrocene complex in the main chain.

Like ferrocene, other transition metal complexes, e.g. B. of Fe ^{lII / l I} , co ^{II / I II} and Ru ^{II / III} , which about

Ligands are bound to a polymer chain and show reversible redoxy obtained, can be used according to the invention.

For example, B. iron, cobaite or ruthenium salts complexed by poly (4) - (or -2-) vinylpyridine or polyvinylbipyridine. Polymer-bound metal salicylates, metal salicylaldehyde, metal salicylaldehyde imine complexes, Pfeiffer complexes complexed via amino acids and the like can be used according to the invention. a. Polymer-bonded metal oxinates, metal glyoximates,

Metal porphyrin and metal phthalocyanine complexes. In this connection, an anodic polymer of pyrrole and tatrasulfonated phthalocyanine iron complex is known (R.A. Bull, F.R. Fan, A.J. Bart, J. Electrochem. Soc. ABC 1636, 1983). Here, however, is the redox active

Complex integrated directly into polypyrrole and is not coupled to another conventional polymer. According to the invention, polymers with reversibly oxidizable and. Can also be used for the production of copolymers or blends. reducible organic groups.

In particular, polymers with quinoid systems in main or side chains can be used. B. a polybenzoquinone tetracarboxylic anhydride that can be reacted with eexamethylene diamine to give benzoquinone main chain polymer or with poly-p-aminostryrol to side-cushion polymers.

The coordination of oxidation and reduction potentials is essential for the combination of the redox-active polymers described with polymers which have a conjugated II-electron system.

The electroactive state of the polymer with isolated redox-active groups can only be exploited if the oxidation potential of the polymer with conjugated II system is lower or its reducing potential is higher than that of the copolymers. The polymer with redox-active groups must either be able to oxidize the conjugated polymer in the oxidized state and thus render it electronically conductive, or else it must be able to reduce a polymer with a conjugated II system in the reduced state.

Polymer-bound ferrocenes can therefore be ideally used as a copolymer or blend for polypyrrole, which, although they do not polymerize, can oxidize and make them conductive. These polypyrrole blends are produced according to the invention by using either anodically or chemically a homogeneous mixture of a dissolved or poured ferrocene polymer. Pyrrole is oxidized together. Electrochemical at potentials of

+ 0.4-0.6 V compared to SCZ initially the ferrocene to posi tiv charged ferricen units oxidized, while at 0.9-1.1 V the polymerization of pyrrole begins. As soon as the polypyrrole has reached a certain conjugation length, it is oxidized by the ferricen under electron and ion transfer to the conductive form. A uniform distribution of the ferrocene in the matrix of the conventional polymer is a prerequisite for an equally homogeneous distribution of the polypyrrole. About 5% by weight or 1-2 mol% ferrocene content is sufficient to produce conductivities of 10 ^-2 to 1 S / cm with even distribution with approx. 4-8 mol% polypyrrole.

According to the invention, the contents of the redox-active component and the proportion of the conductive polymer can be varied within wide limits of approximately 1-90 mol%. Solvents, such as acetonitrile, propylene carbonate, nitromethane, dioxane, 1,2-dimethoxyethane, N-methylpyrrolidone, EMFT or the like, are suitable for electrochemical production, with low water content, together with soluble tetraalkylammonium or lithium salts. The polymerization of pyrrole and the production of blends are also possible from acidic aqueous solution. The anions must be stable to oxidation and must not be less than a certain size. For example, B. BF ₄ -, C10 ₄ -, AsFg6-, SbF ₆ -, PF ₆ - _. SbCl ₆ -, NO ₃ -, ReO ₄ -, TaF ₆ -, ESO ₄ - as well as organic benzene or alkane sulfonic acid anions. According to the invention, blends of ferrocene polymers and polypyrrole can also be produced by chemical oxidation. This is preferably done by means of ferric III salts in a purely organic or aqueous / organic solution or dispersion. FeCl ₃ or Fe (ClO ₄ ) 3.9H ₂ O are suitable for this purpose, but also other oxidizing agents, such as bichromate or H ₂ O ₂ solution.

The reaction with the ferrocene polymer / pyrrole mixture advantageously takes place in acezonitrile or in the two-phase methylene chloride / water system. A particular variant of this invention consists in using a copolymer with ferrocenyl and carboxylic acid or sulfonic acid substituents, in which the charges of the oxidized ferrocene and the polypyrrole can be compensated by the acid anions of the polymer during oxidation. According to the invention, this can be achieved by means of chemical oxidation by means of Eisan-III-acetylacetonate or by electrochemical oxidation, protons and electrons being removed from the polymer in each case.

While polymer-bound ferrocenes have sufficiently high oxidation potentials for polypyrrole and polyaniline, polymer-blown iron III, cobaite III or ruthenium III complexes with higher electro-chemical potential are necessary for polythiophene. Likewise, N-phenyl-substituted pyrroles are only satisfactorily processed into copolymers or blends with these materials. In terms of process, this happens just like in the production of blends from polypyrrole and ferrocene polymers.

The copolymers and blends according to the invention show good mechanical and application properties. They can either be processed from solution during manufacture or can be brought into various forms in a thermoplastic manner. With a suitable selection of copolymers and ferrocene content, they can be processed into molded articles with a smooth, electrically highly conductive surface. They can therefore be used for applications in which a surface structure is scanned electrically optically or capacitively. They are also superior to soot- or metal-filled plastics.

Another important application is the use of the copolymers according to the invention as battery or fuel cell electrodes. This results in the combination of a highly reversible redox system with a conductor capable polymer. Oxidation and reduction cycles of the redox-active component can be used ideally for electrochemical storage purposes. While the electrochemical catalytic effect is used in fuel cells, there is also the possibility of use as chemical catalysts with active transition metal centers. Other possible applications are electrical conductors or low-density semiconductors, materials for electromagnetic shielding, as solar cells or for the antistatic finishing of plastics.

example 1

a) Preparation of ferrocenyl butadiene

8.5 g of AICI ₃ are dissolved in 200 ml of dichloroethane, then 46.5 of ferrocene are added and 54 g of Lithene PM (metal company) dissolved in 200 ml of dichloroethane are added dropwise. After stirring for 2 hours at room temperature, the reaction mixture is poured into 600 ml of methanolic ECl

Filtered polymer, washed and dried. The crude polymer is first oxidized with FeCl ₃ in nitromethane, washed and then used to produce the blend.

b) reaction with pyrrole

Ferrocenylbutadiene in oxidized form is co-poured with pyrrole in dichloroethane and then reacted with aqueous iron III perchlorate solution in a two-phase reaction. The resulting blend is with

Methanol precipitated, washed and dried. It shows thermoplastic formability and elastic behavior. Conductive kait: 10 ^-2 s / cm. Example 2

a) Preparation of ferrocenyl polystyrene

6 g of poly-p-aminostyrene are suspended in 100 ml of 10% aqueous sulfuric acid and mixed with an aqueous solution of 4.2 sodium nitrite. The resulting red-brown suspension of the diazonium salt is concentrated with stirring in a solution of 9.3 g ferrocene in 20 ml. Drops of sulfuric acid and 150 ml of water. Then 6 h at

Stirred at room temperature, washed with suction and dried. Yield: 9.1 g.

b) reaction with pyrrole

3 g of ferrocenyl polystyrene are mixed with 1.1 g of pyrrole in acetonitrile and oxidized by dropwise addition of 17.2 g of ferric perchlorate dissolved in 25 ml of acetonitrile.

The product is stirred into 500 ml of methanol, suction filtered and washed until the filtrate is colorless. Yield after drying: 4.4 g, conductivity: 1 S / cm.

Example 3

3 g of a poly (4-vinylpyridine) iron (III) chloride complex are mixed in acetonitrile with 1.23 g of lithium perchlorate, 1.07 g of pyrrole and oxidized by dropping 5.2 g of iron (III) chloride dissolved in 20 ml of acetonitrile The precipitated polymer product is filtered off, washed with acetonitrile and CH ₂ Cl ₂ and dried. Yield: 3.85 g, conductivity 8 x 10 ^-3 S / cm. Example 4

1.2 g of ferrocene are dissolved in 1 g of AICI ₃ in dichloroethane, mixed with 6 g of polymethacrylic acid ethyl ester in dichloroethane and heated under reflux for one hour.

After cooling, the mixture is poured into ice water, acidified with dil. HCl, the organic phase is separated off in a separating funnel and concentrated by evaporation. The polymer is precipitated by pouring it into methanol, washing with methanol and drying.

6 g of ferrocenylethyl methacrylate are dissolved with 1 g of pyrrole in acetonitrile and a 10% Fe (C10 ₄ ) ₃ solution in acetonitrile is added dropwise until there is no visible reaction. The polymer product is precipitated by pouring it into methanol, washing and drying. Yield: 7.2 g, conductivity: 0.2 S / cm. The material is elastically deformable and thermoplastic.

Example 5

5% vinyliferrocene, 90% ethyl acrylate and 5% acrylic acid are copolymerized with 0.5% AIBN at 82 ° C. The polymer is dissolved in acetonitrile with 10

% By weight of pyrrole and oxidized with a 10% iron III perchlorate solution in acetonitrile. The product is precipitated by pouring it into methanol, washing with water and ethanol and drying. Conductivity: 0.2 S / cm. Example 6

4 g of a polyvinyl alcohol-vinyl acetal copolymer are dissolved in 40 ml of methylene chloride and 2 g of anhydrous pyridine. After adding 2 g of ferrocenecarboxylic acid chloride in

10 ml CH ₂ CI ₂ is stirred for 1 hour at room temperature. The mixture is then stirred into water and extracted with methylene chloride. Drying over sodium sulfate, filtration and stripping the solvent provides an amber colored polymer.

This is dissolved in 250 ml of methylene chloride / acetonitrile 1: 1 and, while stirring, 0.5 g of pyrrole is added, then 8 g of Fe (C10 ₄ ) ₃ dissolved in 10 ml of acetonitrile. A black solution is formed from which the copolymer slowly precipitates. The filling is completed by removing the CH ₂ CI ₂ and pouring the residue into water. The black polymeric product is washed and dried several times. It is elastic and thermoplastic and can be shaped and processed. Conductivity:

0.8 S / cm.

Claims

1 . Copolymers and blends composed essentially of polymeric components (A) without a conjugated ∏ system and polymeric components (3) with a conjugated ∏ system, component A containing redox-active groups which, in the oxidized or reduced state, have an active potential which is suitable for

Oxidation or reduction of component B is sufficient.

2nd Copolymers and blend according to Claim 1, characterized in that component A as redox-active groups б - or ∏ -complexes or chiates, preferably from

Contains transition metals, bound in the main chain and / or in the side chains.

3rd Copolymers and blends according to claim 1 or 2, characterized in that the transition contains metal complexes Fe ^{II l / l I} _, Co ^{I Il / l I} _ and / or Ru ^{III / II} complexes.

4. Copolymers and blends according to one of claims 1 to 3, characterized in that ferrocene complexes are contained as transition complexes.

5. Copolymers and blends according to one of claims 1 to 3, characterized in that metal complexes include metal salicylates, metal salicylaldehyde, metal salicyialdehyde imine complexes, Pfeiffer complexes complexed via amino acids, preferably metal oxinates, metal glyoximate, metal porphyrin and metal phthalocyanine complexes.

6. copolymers and blends according to claim 1, characterized in that component A as redox-active groups quinoid systems, preferably benzoquinone, in the

Main chain and / or bound in the side chain contains.

7. Copolymers and blends according to one of claims 1 to 6, characterized in that component A is substituted with anion-forming groups, preferably with carboxylic acid and / or sulfonic acid or anhydride groups.

8. Copolymers and blends according to one of claims 1 to 7, characterized in that mono copolymers of substituted or unsubstituted pyrrole, thiophene and / or aniline are used as component B.

9. Copolymers and blends according to one of claims 1 to 8, characterized in that component B consists of -C = C-, -C≡C-, -N = N-, -C = N units, mono- or polynuclear aromatics and substituted or unsubstituted pyrrole, thiophene and / or aniline rings.

10th Copolymers and blends according to one of claims 1 to 8, characterized in that oxidatively polymerized, unsubstituted pyrrole is used as component B.

11. Copolymers and blends according to one of claims 1 to 8, characterized in that substituted polypyrroles or copolymers of substituted and unsubstituted pyrroles are used as component B.

12th Copolymers and blends according to claim 11, characterized in that the pyrroles in the N position with

Alkyl, alkynyl and / or in 3-position with alkyl, alkynyl, alkoxy and halogen and in 3, 4-position with alkyl, alkynyl, alkoxy and halogen groups with 1 to 6, preferably 1 to 3 C atoms are substituted.

13. Process for the preparation of copolymers and blends according to one of Claims 1 to 12, characterized in that redox-active compounds with polymerizable substituents are known per se

Way homo- or copolymerized or linked to polymers without a conjugated ∏ system by chemical reaction, and the polymer component A thus obtained is mixed in a manner known per se with the polymer component B or with the monomers forming the components B and then chemically or electrochemically oxidized or reduced.

14. The method according to claim 13, characterized in that a transition metal complex, preferably ferrocene is used as the redox-active compound.

15. The method according to claim 13 or 14, characterized in that substituted or unsubstituted polypyrrole, Ployrhiophen or polyaniline and their copolymers are used as the polymeric component B.

16. The method according to any one of claims 13 to 15, characterized in that for the preparation of the polymeric component A unsubstituted ferrocene with a polymer without a conjugated ∏ system, preferably with polyvinyl chloride, polybutadian, polyacrylate, polymethacrylate, copolymers of maleic anhydride and

Styrene, copolymers of butadiene and styrene or chloromethylated polystyrene is implemented.

17. The method according to claim 13, characterized in that for the production of the polymeric component A ferrocene or ferricenium salts are reacted with diazotized poly-p-aminostyrene.

18. The method according to any one of claims 13 to 15, characterized in that for the preparation of the polymers

Component A ferrocene carboxylic acid or anhydride or

chloride with NH ₂ - or OH-functionalized polymers, preferably with polyvinyl alcohol and copolymers such as partially saponified polyvinyl acetate or polyvinyl butyral.

19. The method according to any one of claims 13 to 15, characterized in that for the production of the polymeric component A ferrocene with polymerizable substituents, preferably vinyl and divinyl ferrocene,

Ferrocenyl acrylate and methacrylate, acrylic acid and

or ferrocene alkyl carboxylic acids, anhydrides or chlorides Methacrylsäurealkylferrocenylester, Ferrocenylmethylacrylamid, Ethinylferrocen, p-Ferrocenylstyrol, p-Ferrocenylphenylacetylen is polymerized in a manner known per se with conventional vinyl monomers.

20. The method according to any one of claims 13 to 15, characterized in that for the preparation of the polymeric component A, dihydroxyalkylferrccenes are reacted with monomeric or oligomeric diisocyanates or prepolymeric epoxy resins, with monomeric dicarboxylic acids or carboxyl-terminated polyesters.

21. The method according to any one of claims 13 to 15, characterized in that for the preparation of the polymeric component A terminally diamino or dihydroxy-substituted monomers or prepolymers with ferrocendicarboxylic acid, dicarboxylic acid ester, dicarboxylic acid chloride or the like. active cicarboxylic acid derivatives, ferrocene diisocyanate or ferrocene dialkyloxirane are implemented.

22. The method according to any one of claims 13 to 15, characterized in that pyrrole, thiophene or aniline are mixed homogeneously with the dissolved or swollen component A and are anodically or chemically oxidized.

23. The method according to any one of claims 1 to 22, characterized in that the polymeric component A contains carboxylic acid and / or sulfonic acid or anhydride groups, which by oxidation in carboxylate and / or

Suifoxylate ions are transferred.

24. The method according to any one of claims 13 to 23, characterized in that the polymeric component A is oxidized before being brought together with the polymeric component B. Use of copolymers and blends according to one of claims 1 to 12 as electrical conductors or semiconductors, in solar cells, for the antistatic finishing of plastics, as materials with low surface resistance, suitable for capacitive scanning, as materials for electromagnetic shielding, as battery electrodes, as electrode materials and as membranes for electrochemistry and fuel cells.